Intermediate film for laminated glass, multilayer intermediate film for laminated glass, and laminated glass

ABSTRACT

An interlayer film for a laminated glass includes a thermoplastic resin and a plasticizer. The ratio of a high molecular weight component with an absolute molecular weight of 1000000 or more in the thermoplastic resin is 7.4% or higher, or the ratio of a high molecular weight component with a polystyrene-equivalent molecular weight of 1000000 or more in the thermoplastic resin is 9% or higher. A first multilayer interlayer for a laminated glass includes an interlayer film for a laminated glass and an interlayer film for a laminated glass that contains it thermoplastic resin and a plasticizer, and is laminated on one face of the interlayer film for a laminated glass.

TECHNICAL FIELD

The present invention relates to an interlayer film for a laminatedglass that contains a thermoplastic resin and a plasticizer. Morespecifically, the present invention relates to an interlayer film for alaminated glass which has excellent sound insulation and hardly causesbubble formation therein; and a multilayer interlayer film for alaminated glass and a laminated glass each including the interlayer filmfor a laminated glass.

BACKGROUND ART

A laminated glass is a safety glass which, even when broken by impactfrom the outside, shatters into few flying glass fragments. For thisreason, a laminated glass is widely used for cars, rail cars, aircrafts,boats and ships, buildings, and the like. The laminated glass isproduced by sandwiching an interlayer film for a laminated glass betweena pair of glass plates.

Patent Document 1 provides one example of the interlayer film for alaminated glass; that is, Patent Document 1 teaches an interlayer filmcontaining 100 parts by weight of a polyvinyl acetal resin and 20 to 60parts by weight of a mixture of triethylene glycol mono-2-ethylhexanoateand triethylene glycol di-2-ethylhexanoate.

Patent Document 2 teaches a sound insulation layer that contains 100parts by weight of a polyvinyl acetal resin having a degree ofacetalization of 60 to 85 mol %, 0.001 to 1.0 part by weight of at leastone metal salt of alkali metal salts and alkaline earth metal salts, andat least 30 parts by weight of a plasticizer. This sound insulationlayer alone can be used as an interlayer film.

Patent Document 2 also teaches a multilayer interlayer film in which thesound insulation layer and another layer are laminated. The anotherlayer laminated on the sound insulation layer contains 100 parts byweight of a polyvinyl acetal resin having a degree of acetalization of60 to 85 mol %, 0.001 to 1.0 part by weight of at least one metal saltamong alkali metal salts and alkaline earth metal salts, and 30 parts byweight or less of a plasticizer.

Patent Document 1: JP 2001-097745 A

Patent Document 2: JP 2007-070200 A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

A laminated glass formed with use of the interlayer film of PatentDocument 1 has insufficient sound insulation for sound with a frequencyof about 2000 Hz, and therefore may not prevent decrease in soundinsulation when the coincidence effect occurs. Also, the soundinsulation of the laminated glass is sometimes insufficient at around20° C.

Here, the coincidence effect refers to a phenomenon in which, uponincidence of sound waves on a glass plate, transverse waves due torigidity and inertia of the glass plate spread on the glass surface toresonate with the incidence sound, whereby the sound is transmitted.

A laminated glass formed with use of a single layer of the soundinsulation layer as an interlayer film disclosed in Patent Document 2may provide insufficient sound insulation at around 20° C.

Moreover, in the case of forming a laminated glass using the multilayerinterlayer film of Patent Document 2 in which a sound insulation layerand another layer are laminated, the sound insulation of the laminatedglass at around 20° C. can be increased to some extent. However, sincethe multilayer interlayer film includes the sound insulation layer,bubble formation may occur in the laminated glass formed with use of themultilayer interlayer film.

Meanwhile, considerations have been made in recent years to increase theamount of the plasticizer in an interlayer film for increasing the soundinsulation of a laminated glass. Increasing the amount of theplasticizer can improve the sound insulation of the laminated glass.However, the increase in the amount of the plasticizer sometimes causesbubble formation in the laminated glass.

The present invention aims to provide an interlayer film for a laminatedglass which can give a laminated glass capable of suppressing bubbleformation and bubble growth; and a multilayer interlayer film for alaminated glass and a laminated glass each including the interlayer filmfor a laminated glass.

The present invention specifically aims to provide an interlayer filmfor a laminated glass which can give a laminated glass having excellentsound insulation and capable of suppressing bubble formation and bubblegrowth; and a multilayer interlayer film for a laminated glass and alaminated glass each including the interlayer film for a laminatedglass.

Means for Solving the Problems

A broad aspect of the present invention is an interlayer film for alaminated glass, including a thermoplastic resin and a plasticizer,wherein the thermoplastic resin contains a high molecular weightcomponent with an absolute molecular weight of 1000000 or more, and theratio of the high molecular weight component in the thermoplastic resinis 7.4% or higher, or the thermoplastic resin contains a high molecularweight component with a polystyrene-equivalent molecular weight of1000000 or more, and the ratio of the high molecular weight component inthe thermoplastic resin is 9% or higher.

In a specific aspect of the interlayer film for a laminated glassaccording to the present invention, the interlayer film for a laminatedglass includes a thermoplastic resin and a plasticizer, wherein thethermoplastic resin contains a high molecular weight component with anabsolute molecular weight of 1000000 or more, and the ratio of the highmolecular weight component in the thermoplastic resin is 7.4% or higher.

In another specific aspect of the interlayer film for a laminated glassaccording to the present invention, the thermoplastic resin is apolyvinyl acetal resin.

In another specific aspect of the interlayer film for a laminated glassaccording to the present invention, the polyvinyl acetal resin has ahydroxyl content of at most 31 mol %.

In a yet another specific aspect of the interlayer film for a laminatedglass according to the present invention, an amount of the plasticizerfor each 100 parts by weight of the thermoplastic resin is within arange of 40 to 80 parts by weight.

In a specific aspect of the interlayer film for a laminated glassaccording to the present invention, the interlayer film for a laminatedglass includes a thermoplastic resin and a plasticizer, wherein thethermoplastic resin contains a high molecular weight component with apolystyrene-equivalent molecular weight of 1000000 or more, and theratio of the high molecular weight component in the thermoplastic resinis 9% or higher.

A multilayer interlayer film for a laminated glass according to thepresent invention includes the interlayer film for a laminated glassstructured according to the present invention as a first interlayer filmfor a laminated glass, and a second interlayer film for a laminatedglass that contains a thermoplastic resin and a plasticizer and islaminated on one face of the first interlayer film for a laminatedglass.

In a specific aspect of the multilayer interlayer film for a laminatedglass according to the present invention, an amount of the plasticizerfor each 100 parts by weight of the thermoplastic resin in the firstinterlayer film for a laminated glass is larger than an amount of theplasticizer for each 100 parts by weight of the thermoplastic resin inthe second interlayer film for a laminated glass.

In another specific aspect of the multilayer interlayer film for alaminated glass according to the present invention, the multilayerinterlayer film for a laminated glass further includes a thirdinterlayer film for a laminated glass that contains a thermoplasticresin and a plasticizer and is laminated on the other face of the firstinterlayer film for a laminated glass.

In a yet another specific aspect of the multilayer interlayer film for alaminated glass according to the present invention, an amount of theplasticizer for each 100 parts by weight of the thermoplastic resin inthe first interlayer film for a laminated glass is larger than an amountof the plasticizer for each 100 parts by weight of the thermoplasticresin in the third interlayer film for a laminated glass.

Meanwhile, for example, the plasticizer may migrate between the firstinterlayer film for a laminated glass and the second interlayer film fora laminated glass.

In another specific aspect of the multilayer interlayer film for alaminated glass according to the present invention, the thermoplasticresin in the first interlayer film for a laminated glass is a polyvinylacetal resin, and the polyvinyl acetal resin has a degree of acetylationof at most 8 mol % and a degree of acetalization of 70 mol % or higher.

In a yet another specific aspect of the multilayer interlayer film for alaminated glass according to the present invention, the thermoplasticresin in the first interlayer film for a laminated glass is a polyvinylacetal resin, and the polyvinyl acetal resin has a degree of acetylationof higher than 8 mol %.

The laminated glass according to the present invention includes firstlaminated glass component, second laminated glass component, and aninterlayer film or a multilayer interlayer film sandwiched between thefirst laminated glass component and the second laminated glasscomponent, wherein the interlayer film or the multilayer interlayer filmis the interlayer film for a laminated glass or the multilayerinterlayer film for a laminated glass structured according to thepresent invention.

Effect of the Invention

The interlayer film for a laminated glass according to the presentinvention includes a thermoplastic resin and a plasticizer, wherein thethermoplastic resin contains a high molecular weight component with anabsolute molecular weight of 1000000 or more, and the ratio of the highmolecular weight component in the thermoplastic resin is 7.4% or higher,or the thermoplastic resin contains a high molecular weight componentwith a polystyrene-equivalent molecular weight of 1000000 or more, andthe ratio of the high molecular weight component in the thermoplasticresin is 9% or higher. Therefore, if the interlayer film for a laminatedglass is used for forming a laminated glass, bubble formation and bubblegrowth in the laminated glass can be suppressed. Moreover, the laminatedglass can have an enhanced sound insulation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view schematically illustrating a multilayerinterlayer film for a laminated glass according to one embodiment of thepresent invention.

FIG. 2 is a cross-sectional view schematically illustrating aninterlayer film for a laminated glass according to one embodiment of thepresent invention.

FIG. 3 is a cross-sectional view schematically illustrating one exampleof a laminated glass including the multilayer interlayer film for alaminated glass illustrated in FIG. 1.

MODE(S) FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail.

The interlayer film for a laminated glass of the present inventioncontains a thermoplastic resin and a plasticizer. The thermoplasticresin contains either a high molecular weight component with an absolutemolecular weight of 1000000 or more (hereinafter also referred to ashigh molecular weight component X) or a high molecular weight component(hereinafter also referred to as high molecular weight component Y) witha polystyrene-equivalent molecular weight (hereinafter also referred toas molecular weight y) of 1000000 or more. The high molecular componentsX and Y each are a thermoplastic resin. In the interlayer film for alaminated glass according to the present invention, the ratio of thehigh molecular weight component X in the thermoplastic resin is 7.4% orhigher, or the ratio of the high molecular weight component Y in thethermoplastic resin is 9% or higher.

FIG. 1 is a cross-sectional view schematically illustrating a multilayerinterlayer film for a laminated glass according to one embodiment of thepresent invention.

A multilayer interlayer film 1 illustrated in FIG. 1 includes a firstinterlayer film 2, a second interlayer film 3 laminated on one face 2 a(first face) of the first interlayer film 2, and a third interlayer film4 laminated on the other face 2 b (second face) of the first interlayerfilm 2. The multilayer film 1 is used to prepare a laminated glass. Themultilayer interlayer film 1 is a multilayer interlayer film for alaminated glass. The first interlayer film 2, the second interlayer film3 and the third interlayer film 4 are interlayer films for a laminatedglass.

In the present embodiment, the first interlayer film 2 is anintermediate layer, and the second interlayer film 3 and the thirdinterlayer film 4 are surface layers. Preferably, both the secondinterlayer film 3 and the third interlayer film 4 are used like thisexample. Only the second interlayer film 3 may be used without using thethird interlayer film 4. Other interlayer films for a laminated glassmay be further laminated on the outer surface 3 a of the secondinterlayer film 3 and the outer surface 4 a of the third interlayer film4, respectively.

The first interlayer film 2, the second interlayer film 3 and the thirdinterlayer film 4 each contain a thermoplastic resin and a plasticizer.The thermoplastic resin contained in the first interlayer film 2contains the high molecular weight component X with an absolutemolecular weight of 1000000 or more, and the ratio of the high molecularcomponent X in the thermoplastic resin is 7.4% or higher. Alternatively,the thermoplastic resin contained in the first interlayer film 2 maycontain the high molecular weight component Y with the molecular weighty of 1000000 or more, and the ratio of the high molecular weightcomponent Y in the thermoplastic resin may be 9% or higher.

The ratio of the high molecular weight component X in the thermoplasticresin is defined by the ratio expressed in percentage (%) of an area ofthe region corresponding to the high molecular weight component X in thepeak area of the thermoplastic resin that is obtained upon measurementof the absolute molecular weight. The ratio of the high molecular weightcomponent Y in the thermoplastic resin is defined by the ratio expressedin percentage (%) of an area of the region corresponding to the highmolecular weight component Y in the peak area of the thermoplastic resinthat is obtained upon measurement of the polystyrene-equivalentmolecular weight.

The compositions of the second interlayer film 3 and the thirdinterlayer film 4 are preferably different from the composition of thefirst interlayer film 2. The thermoplastic resin contained in the secondinterlayer film 3 and the third interlayer film 4 each may contain thehigh molecular weight component X with an absolute molecular weight of1000000 or more, and the ratio of the high molecular weight component Xin the thermoplastic resin may be 7.4% or higher, or may contain thehigh molecular weight component Y with the molecular weight y of 1000000or more, and the ratio of the high molecular weight component Y in thethermoplastic resin may be 9% or higher.

FIG. 2 is a cross-sectional view schematically illustrating aninterlayer film for a laminated glass according to one embodiment of thepresent invention.

An interlayer film 21 for a laminated glass illustrated in FIG. 2 is asingle-layer interlayer film. The interlayer film 21 is used forpreparing a laminated glass. The interlayer film 21 is an interlayerfilm for a laminated glass.

The interlayer film 21 contains a thermoplastic resin and a plasticizer.The thermoplastic resin contained in the interlayer film 21 contains thehigh molecular weight component X with an absolute molecular weight of1000000 or more, and the ratio of the high molecular component X in thethermoplastic resin is 7.4% or higher. Alternatively, the thermoplasticresin contained in the interlayer film 21 may contain the high molecularweight component Y with the molecular weight y of 1000000 or more, andthe ratio of the high molecular weight component Y in the thermoplasticresin may be 9% or higher.

The multilayer interlayer film 1 is preferred to the single-layerinterlayer film 21. In the case that the second interlayer film 3 andthe third interlayer film 4 are laminated on both sides of the firstinterlayer film 2, even if the adhesion force of the first interlayerfilm 2 is low, bonding strength between the multilayer interlayer film 1and the laminated glass components can be enhanced by increasing theadhesion force of the second interlayer film 3 and the third interlayerfilm 4. As a result, the penetration resistance of the laminated glasscan be further increased.

In the case of the multilayer interlayer film 1, bubble formation moreeasily occurs in the laminated glass as compared with the single-layerinterlayer film 21. In especially the case where the amount of theplasticizer for each 100 parts by weight of the thermal plastic resin inthe first interlayer film 2 is larger than the amount of the plasticizerfor each 100 parts by weight of thermoplastic resin in the secondinterlayer film 3 and the third interlayer film 4, bubble formation ismore likely to occur. Further, once bubbles are generated, the bubblestend to grow with the generated bubbles as the core. However, since thethermoplastic resin contained in the first interlayer film 2 contains aspecific rate of the high molecular weight component with an absolutemolecular weight of 1000000 or more in the present embodiment, bubbleformation can be prevented from occurring in the laminated glass. Also,if the thermoplastic resin contained in the first interlayer 2 containsthe specific ratio of the high molecular weight component Y with themolecular weight y of 1000000 or more, bubble formation can be preventedfrom occurring in the laminated glass.

In terms of further increasing the sound insulation of the laminatedglass and further suppressing bubble formation and bubble growth, thelower limit of the ratio of the high molecular weight component X withan absolute molecular weight of 1000000 or more in the thermoplasticresin contained in the interlayer films 1, 2, and 21 is preferably 8%,more preferably 8.5%, still more preferably 9%, particularly preferably9.5%, and most preferably 10%. The ratio of the high molecular weightcomponent X that can further increase the sound insulation of thelaminated glass and further suppress bubble formation and bubble growthis preferably 11% or higher, more preferably 12% or higher, furtherpreferably 14% or higher, and particularly preferably 16% or higher. Thepreferable upper limit of the ratio of the high molecular weightcomponent X is not particularly limited, and the upper limit ispreferably 40%, more preferably 30%, and still more preferably 25%.

In the case that the thermoplastic resins contained in the interlayerfilms 1, 2, and 21 each contain the high molecular weight component Ywith the molecular weight y of 1000000 or more, the lower limit of thehigh molecular weight component Y with the molecular weight y of 1000000or more in the thermoplastic resins contained in the single-layerinterlayer film containing the high molecular weight component Y and theinterlayer film (first interlayer film for a laminated glass) containingthe high molecular weight component Y among the multilayer interlayerfilm is preferably 10%, more preferably 11%, still more preferably11.5%, and particularly preferably 12%. The ratio of the high molecularweight component Y that can further increase the sound insulation of thelaminated glass and further suppress bubble formation and bubble growthis preferably 12.5% or higher, more preferably 13.5% or higher, stillmore preferably 14% or higher, particularly preferably 15% or higher,and most preferably 18% or higher. The upper limit of the ratio of thehigh molecular weight component Y is not particularly limited, and theupper limit is preferably 40%, more preferably 30%, and still morepreferably 25%. If the ratio of the high molecular weight component Y isat least the lower limit, the sound insulation of the laminated glasscan be further increased, and bubble formation and bubble growth can befurther suppressed.

In terms of further increasing the penetration resistance of thelaminated glass, the lower limit of the thickness of the multilayerinterlayer film 1 and single-layer interlayer film 21 is preferably 0.05mm, and more preferably 0.25 mm. The upper limit of the thickness ispreferably 3 mm, and more preferably 1.5 mm. If the thickness of themultilayer interlayer film 1 and single-layer interlayer film 21 satisfythe preferable lower limit and the preferably upper limit, thepenetration resistance and the transparency of the laminated glass canbe further increased.

(Thermoplastic Resin)

The kinds of the thermoplastic resins contained in the interlayer films2 to 4, and 21 are not particularly limited. Only one kind ofthermoplastic resin may be used, and two or more kinds thereof may beconcomitantly used.

Examples of the thermoplastic resin include polyvinyl acetal resins,ethylene-vinyl acetate copolymer resins, ethylene-acryl copolymerresins, polyurethane resins, and polyvinyl alcohol resins.

The minimum weight average molecular weight of the thermoplastic resinis preferably 100000, and more preferably 300000. The maximum weightaverage molecular weight is preferably 10000000, and more preferably5000000. If the weight average molecular weight of the thermoplasticresin is lower than the minimum value, the strength of the interlayerfilm may decrease. If the weight average molecular weight of thethermoplastic resin is higher than the maximum value, the strength ofthe interlayer film to be produced may be too high. The weight averagemolecular weight indicates a polystyrene-equivalent weight averagemolecular weight measured by gel permeation chromatography (GPC).

Preferably, the thermoplastic resin is a polyvinyl acetal resin.Concomitant use of the polyvinyl acetal resin and the plasticizer canfurther increase the adhesive force of the interlayer film or themultilayer interlayer film to the laminated glass components. If thethermoplastic resin is a polyvinyl acetal resin, the high molecularweight components X and Y are polyvinyl acetal resins.

Moreover, if the thermoplastic resin is a polyvinyl acetal resin, bubbleformation tends to occur in the laminated glass which includes theinterlayer film or the multilayer interlayer film. However, as thepolyvinyl acetal resin contains the high molecular weight component Xwith an absolute molecular weight of 1000000 or more or the highmolecular weight component Y with the molecular weight y of 1000000 ormore at the specific ratio, bubble formation and bubble growth can besufficiently suppressed in the laminated glass which includes theinterlayer film for a laminated glass.

In the case that the interlayer film 2, which is an intermediate layer,and the single-layer interlayer film 21 contain a polyvinyl acetalresin, the hydroxyl content (the amount of the hydroxyl group) in thepolyvinyl acetal resin contained in the interlayer films 2 and 21 ispreferably at most 31 mol %. In this case, the sound insulation of thelaminated glass can be further increased. If the hydroxyl content of thepolyvinyl acetal resin is low, the hydrophilicity of the polyvinylacetal resin is low. Hence, the amount of the plasticizer can beincreased and, as a result, the sound insulation of the laminated glasscan be further increased.

The minimum hydroxyl content of the polyvinyl acetal resin in theinterlayer films 2 and 21 is preferably 13 mol %, more preferably 18 mol%, still more preferably 20 mol %, and particularly preferably 21.5 mol%. The maximum hydroxyl content is preferably 30 mol %, more preferably28 mol %, and particularly preferably 26 mol %. If the hydroxyl contentsatisfies the preferable minimum amount, the adhesion force of theinterlayer films 2 and 21 can be further increased. If the hydroxylcontent satisfies the preferable maximum amount, the sound insulation ofthe laminated glass can be further increased. Moreover, the multilayerinterlayer film 1 and the interlayer film 21 can have higherflexibility, and thus the multilayer interlayer film 1 and theinterlayer film 21 can show even higher handling properties.

In the case that the interlayer films 3 and 4 each contain a polyvinylacetal resin, the minimum hydroxyl content of the polyvinyl acetal resinin each of the interlayer films 3 and 4 is preferably 26 mol %, morepreferably 27 mol %, and still more preferably 28 mol %. The maximumhydroxyl content is preferably 35 mol %, more preferably 33 mol %, stillmore preferably 32 mol %, and particularly preferably 31.5 mol %. If thehydroxyl content satisfies the preferable minimum value, the adhesionforce of the interlayer films 3 and 4 can be further increased. If thehydroxyl content satisfies the preferable maximum value, the multilayerinterlayer film 1 can have higher flexibility, and can therefore showeven higher handling properties.

In terms of further increasing the sound insulation of the laminatedglass, the hydroxyl content of the polyvinyl acetal resin in theinterlayer film 2 is preferably lower than the hydroxyl content of thepolyvinyl acetal resin in each of the interlayer films 3 and 4. In termsof further increasing the sound insulation of the laminated glass, thehydroxyl content of the polyvinyl acetal resin in the interlayer film 2is lower than the hydroxyl content of the polyvinyl acetal resin in eachof the interlayer films 3 and 4 preferably by 1 mol % or lower, morepreferably by 3 mol % or lower, and still more preferably by 5 mol % orlower, and particularly preferably 7 mol % or lower.

The hydroxyl content of the polyvinyl acetal resin is a value of themolar fraction in percentage (mol %) determined by dividing the amountof ethylene group having the hydroxyl group bonded thereto by the totalamount of the ethylene group in the main chain. The amount of ethylenegroup having the hydroxyl group bonded thereto can be determined by, forexample, determining the amount of ethylene group having the hydroxylgroup bonded thereto in the polyvinyl acetal resin according to themethod based on JIS K6726 “Testing Methods for Polyvinyl alcohol”.

In the case that the interlayer films 2 and 21 each contain a polyvinylacetal resin, the lowest degree of acetylation (amount of acetyl) of thepolyvinyl acetal resin in each of the interlayer films 2 and 21 ispreferably 0.1 mol %, more preferably 0.4 mol %, and still morepreferably 0.8 mol %. The highest degree is 30 mol %, more preferably 25mol %, still more preferably 20 mol %, and particularly preferably 15mol %. In the case that the interlayer films 3 and 4 each contain apolyvinyl acetal resin, the lowest degree of acetylation of thepolyvinyl acetal resin in each of the interlayer films 3 and 4 ispreferably 0.1 mol %, and more preferably 0.4 mol %. The highest degreeis preferably 20 mol %, more preferably 5 mol %, still more preferably 2mol %, and particularly preferably 1.5 mol %. If the degree ofacetylation satisfies the preferable lowest degree, the compatibility ofthe polyvinyl acetal resin and the plasticizer is further increased, andthe glass-transition temperature of the interlayer film and themultilayer interlayer film can be sufficiently decreased. If the degreeof acetylation satisfies the preferable highest degree, the humidityresistance of the interlayer film and the multilayer interlayer film canbe further increased.

In terms of further increasing the sound insulation of the laminatedglass, the degree of acetylation of the polyvinyl acetal resin in theinterlayer film 2 is preferably larger than the degree of acetylation ofthe polyvinyl acetal resin in each of the interlayer films 3 and 4. Interms of even further increasing the sound insulation of the laminatedglass, the degree of acetylation of the polyvinyl acetal resin in theinterlayer film 2 is preferably larger than the degree of acetylation ofthe polyvinyl acetal resin in each of the interlayer films 3 and 4preferably by 0.1 mol % or higher, more preferably by 1 mol % or higher,still more preferably by 5 mol % or higher, and particularly preferablyby 10 mol % or higher.

In terms of even further increasing the sound insulation of thelaminated glass, the degree of acetylation of the polyvinyl acetal resinin the interlayer film 2 is preferably larger than the degree ofacetylation of the polyvinyl acetal resin in the interlayer films 3 and4.

The degree of acetylation is a value of the molar fraction in percentage(mol %) determined by dividing, by the total amount of ethylene group inthe main chain, a value resulting from subtracting the amount ofethylene group having the acetal group bonded thereto and the amount ofethylene group having the hydroxyl group bonded thereto from the totalamount of ethylene group in the main chain. The amount of ethylene grouphaving the acetal group bonded thereto can be determined based on JISK6728 “Testing Methods for Polyvinyl butyral”, for example.

In the case that the interlayer films 2 and 21 each containing the highmolecular weight component with an absolute molecular weight of 1000000or more at the specific ratio each contain a polyvinyl acetal resin, thelowest degree of acetalization of the polyvinyl acetal resin in each ofthe interlayer films 2 and 21 is preferably 50 mol %, more preferably 53mol %, still more preferably 60 mol %, and particularly preferably 63mol %. The highest degree is preferably 85 mol %, more preferably 80 mol%, and still more preferably 78 mol %. In the case that the interlayerfilms 3 and 4 each contain a polyvinyl acetal resin, the lowest degreeof acetalization of the polyvinyl acetal resin in each of the interlayerfilms 3 and 4 is preferably 55 mol %, more preferably 60 mol %, stillmore preferably 65 mol %, and particularly preferably 67 mol %. Thehighest degree is preferably 75 mol %, more preferably 72 mol %, andstill more preferably 71 mol %. If the degree of acetalization satisfiesthe preferable lowest degree, the compatibility of the polyvinyl acetalresin and the plasticizer is further increased, and the glass-transitiontemperature of the interlayer film and the multilayer interlayer filmcan be sufficiently decreased. If the degree of acetalization satisfiesthe preferable highest degree, the reaction time required to produce apolyvinyl acetal resin can be shortened.

The degree of acetalization is a value of the molar fraction inpercentage (mol %) determined by dividing the amount of ethylene grouphaving the acetal group bonded thereto by the total amount of ethylenegroup in the main chain.

The degree of acetalization is calculated by first measuring the amountsof the acetyl and the vinyl alcohol (hydroxyl content) by the methodaccording to JIS K6728 “Testing Methods for Polyvinyl butyral”,calculating the molar fraction from the measured amounts, andsubtracting the amounts of acetyl and vinyl alcohol from 100 mol %.

Meanwhile, in the case that the polyvinyl acetal resin is a polyvinylbutyral resin, the degree of acetalization (degree of butyralization)and the amount of the acetyl are calculated based on the resultsmeasured by the method according to JIS K6728 “Testing Methods forPolyvinyl butyral”.

In the case that the interlayer films 2 and 21 each contain a polyvinylacetal resin, for further increasing the sound insulation of theinterlayer films 2 and 21, the polyvinyl acetal resin is preferably apolyvinyl acetal resin A having the degree a of acetylation of at most 8mol % and the degree a of acetalization of 70 mol % or higher, orpreferably a polyvinyl acetal resin B having the degree b of acetylationof higher than 8 mol %. The polyvinyl acetal resin may be the polyvinylacetal resin A having the degree a of acetylation of at most 8 mol % andthe degree a of acetalization of 70 mol % or higher, or may be thepolyvinyl acetal resin B having the degree b of acetylation of higherthan 8 mol %.

The highest degree a of acetylation of the polyvinyl acetal resin A is 8mol %, preferably 7.5 mol %, more preferably 7 mol %, still morepreferably 6.5 mol %, and particularly preferably 5 mol %. The lowestdegree is preferably 0.1 mol %, more preferably 0.5 mol %, still morepreferably 0.8 mol %, and particularly preferably 1 mol %. If the degreea of acetylation is at most the highest degree and at least the lowestdegree, migration of the plasticizer can be easily controlled, and thesound insulation of the laminated glass can be further increased.

The lowest degree a of acetalization of the polyvinyl acetal resin A is70 mol %, preferably 70.5 mol %, more preferably 71 mol %, still morepreferably 71.5 mol %, and particularly preferably 72 mol %. The highestdegree is preferably 85 mol %, more preferably 83 mol %, furtherpreferably 81 mol %, and particularly preferably 79 mol %. If the degreea of acetalization is the lowest degree or higher, the sound insulationof the laminated glass can be further increased. If the degree a ofacetalization is at most the highest degree, the reaction time requiredto produce a polyvinyl acetal resin A can be shortened.

The minimum value of the hydroxyl content a of the polyvinyl acetalresin A is preferably 18 mol %, more preferably 19 mol %, still morepreferably 20 mol %, and particularly preferably 21 mol %. The maximumvalue is preferably 31 mol %, more preferably 30 mol %, still morepreferably 29 mol %, and particularly preferably 28 mol %. If thehydroxyl content a satisfies the preferable minimum value, theinterlayer film can provide even higher adhesion. Further, if thehydroxyl content a satisfies the preferable maximum value, the soundinsulation of the laminated glass can be further increased.

The polyvinyl acetal resin A is preferably a polyvinyl butyral resin.

The degree b of acetylation of the polyvinyl acetal resin B is higherthan 8 mol %. The lowest degree b is preferably 9 mol %, more preferably9.5 mol %, still more preferably 10 mol %, and particularly preferably10.5 mol %. The highest degree of the degree is preferably 30 mol %,more preferably 28 mol %, still more preferably 26 mol %, andparticularly preferably 24 mol %. If the degree b of acetylation is atleast at the lowest degree, the sound insulation of the laminated glasscan be further increased. If the degree b of acetylation is at most thehighest degree, the reaction time required to produce the polyvinylacetal resin B can be shortened.

The lowest degree b of acetalization of the polyvinyl acetal resin B ispreferably 50 mol %, more preferably 53 mol %, still more preferably 55mol %, and particularly preferably 60 mol %. The highest degree ispreferably 80 mol %, more preferably 78 mol %, still more preferably 76mol %, and particularly preferably 74 mol %. If the degree b ofacetalization is at least the lowest degree, the sound insulation of thelaminated glass can be further increased. If the degree b ofacetalization is at most the highest degree, the reaction time requiredto produce the polyvinyl acetal resin B can be shortened.

The minimum value of the hydroxyl content b of the polyvinyl acetalresin B is preferably 18 mol %, more preferably 19 mol %, still morepreferably 20 mol %, and particularly preferably 21 mol %. The maximumvalue is preferably 31 mol %, more preferably 30 mol %, still morepreferably 29 mol %, and particularly preferably 28 mol %. If thehydroxyl content b satisfies the preferable minimum value, theinterlayer film can provide even higher adhesion. Further, if thehydroxyl content b satisfies the preferable maximum value, theinterlayer film can provide even higher sound insulation of thelaminated glass.

The polyvinyl acetal resin B is preferably a polyvinyl butyral resin.

The polyvinyl acetal resin A and the polyvinyl acetal resin B each areobtained by acetalizing a polyvinyl alcohol with an aldehyde. Thealdehyde is preferably a C1 to C10 aldehyde, and is more preferably a C4or C5 aldehyde.

The polyvinyl acetal resin A and the polyvinyl acetal resin B each arepreferably a polyvinyl acetal resin which can be obtained by acetalizingwith an aldehyde a polyvinyl alcohol X having a degree of polymerizationof 1600 to 3000. The degree of polymerization of the polyvinyl alcohol Xis preferably 1700 or higher, preferably higher than 1700, preferably1800 or higher, preferably 2000 or higher, preferably 2100 or higher,preferably 2200 or higher, preferably 2900 or lower, and preferably 2800or lower because those degrees can sufficiently suppress bubbleformation and bubble growth. The degree of polymerization means anaverage degree of polymerization. Meanwhile, the average degree ofpolymerization can be obtained by the method according to JIS K6726“Testing Methods for Polyvinyl alcohol”.

(Method of Producing Polyvinyl Acetal Resin Containing High MolecularWeight Component X with an Absolute Molecular Weight of 1000000 or Moreor High Molecular Weight Component Y with a Molecular Weight y of1000000 or More)

The following will describe a concrete method of producing a polyvinylacetal resin containing the high molecular weight component X with anabsolute molecular weight of 1000000 or more or the high molecularweight component Y with the molecular weight y of 1000000 or more as anexample of a thermoplastic resin that contains at least the lowest ratioof the high molecular weight component X with an absolute molecularweight of 1000000 or more or the high molecular weight component Y withthe molecular weight y of 1000000 or more.

First, a polyvinyl alcohol is prepared. The polyvinyl alcohol can beobtained by, for example, saponification of polyvinyl acetate. Thesaponification degree of the polyvinyl alcohol is generally in the rangeof 70 to 99.9 mol %, preferably 75 to 99.8 mol %, and more preferably 80to 99.8 mol %.

The lowest degree of polymerization of the polyvinyl alcohol ispreferably 200, more preferably 500, still more preferably 1000, andparticularly preferably 1500. The highest degree is preferably 3000,more preferably 2900, still more preferably 2800, and particularlypreferably 2700. If the degree of polymerization is too low, thepenetration resistance of the laminated glass tends to deteriorate. Ifthe degree of polymerization is too high, molding of the interlayer filmmay be difficult.

Next, the polyvinyl alcohol is reacted with an aldehyde with a catalystfor acetalization of the polyvinyl alcohol. A solution containing thepolyvinyl alcohol may be used. Examples of the solvent to be used forthe solution containing the polyvinyl alcohol include water.

Preferable examples of the method of producing the polyvinyl acetalresin contained in each of the interlayer films 2 and 21 include aproduction method in which a polyvinyl alcohol is reacted with analdehyde with a catalyst for acetalization of the polyvinyl alcohol sothat a polyvinyl acetal resin is prepared.

The method of producing the interlayer films 2 and 21 preferablyincludes a step of reacting a polyvinyl alcohol with an aldehyde with acatalyst for acetalization of the polyvinyl alcohol so that a polyvinylacetal resin is prepared; and a step of preparing an interlayer film fora laminated glass using a mixture of the above-obtained polyvinyl acetalresin and a plasticizer. A multilayer interlayer film can be prepared bylaminating the second interlayer film for a laminated glass on theinterlayer film for a laminated glass, optionally followed by laminationof the third interlayer film for a laminated glass, if desired, duringthe process of preparing the interlayer film for a laminated glass orafter preparing the interlayer film for a laminated glass. Moreover, amultilayer interlayer film may be produced by coextrusion of theinterlayer film 21 and the second interlayer film for a laminated glass.Furthermore, a multilayer interlayer film may be produced by coextrusionof the interlayer film 21, the second interlayer film for a laminatedglass, and the third interlayer film for a laminated glass.

The aldehyde is not particularly limited. Generally, a C1 to 010aldehyde is suitably used as the above aldehyde. Examples of the C1 toC10 aldehyde include propionaldehyde, n-butyraldehyde, isobutyraldehyde,N-valeraldehyde, 2-ethylbutyraldehyde, n-hexyl aldehyde, n-octylaldehyde, n-nonyl aldehyde, n-decyl aldehyde, formaldehyde,acetaldehyde, and benzaldehyde. Particularly, n-butyraldehyde, n-hexylaldehyde, and n-valeraldehyde are preferable, and n-butyraldehyde ismore preferable. Each of the above aldehydes may be used alone, or twoor more of the aldehydes may be used in combination.

In terms of easy preparation of the polyvinyl acetal resin containingthe specific ratio of the high molecular weight component X with anabsolute molecular weight of 1000000 or more or the high molecularweight component Y with the molecular weight y of 1000000 or more, forexample, before or during the acetalization reaction using the aldehyde,the following methods may be exemplified: a method in which acrosslinking agent such as dialdehyde is added for crosslinking a mainchain of the adjacent polyvinyl alcohol; a method in which an excessiveamount of aldehyde is added to promote intermolecular acetalization; anda method of adding a polyvinyl alcohol with a high polymerizationdegree. Those methods may be performed alone, or two or more kindsthereof may be performed in combination.

The catalyst is preferably an acid catalyst. Examples of the acidcatalyst include nitric acid, hydrochloric acid, sulfuric acid,phosphoric acid, and para-toluene sulfonic acid.

The polystylene-equivalent molecular weight refers to a molecular weightequivalent to polystyrene as determined by gel permeation chromatography(GPC). The ratio (%) of the high molecular weight component Y with themolecular weight y of 1000000 or more in the thermoplastic resin iscalculated from the ratio of an area corresponding to the region of themolecular weight y of 1000000 or more in the peak area detected by an RIdetector during the measurement of the polystyrene-equivalent molecularweight of the thermoplastic resin by GPC. The peak area refers to anarea between the peak of the component measured and a base line.

The polystyrene-equivalent molecular weight is measured, for example, asfollows.

In order to determine the polystyrene-equivalent molecular weight, GPCmeasurement is performed on the polystyrene standard samples whosemolecular weights are known. The polystyrene standard samples used(“Shodex Standard SM-105” and “Shodex Standard SH-75” produced by ShowaDenko K.K.) are 14 samples having weight-average molecular weights of580, 1260, 2960, 5000, 10100, 21000, 28500, 76600, 196000, 630000,1130000, 2190000, 3150000, and 3900000. An approximation straight line,obtained by plotting the weight-average molecular weights relative tothe elution times shown by the peak tops of the respective standardsample peaks, can be used as a calibration curve. For example, in thecase of measuring the ratio (%) of the high molecular weight component Ywith the molecular weight y of 1000000 or more in the thermoplasticresin in the multilayer interlayer film that is formed by laminating thesurface layer, the intermediate layer, and the surface layer in thestated order, the surface layers and the intermediate layer areseparated from the multilayer interlayer film that has been left tostand in a constant temperature and humidity room (humidity: 30% (±3%),temperature: 23° C.) for one month. The separated intermediate layer isdissolved in tetrahydrofuran (THF) so that 0.1% by weight of a solutionis prepared. The solution is analyzed with a GPC device to determine thepeak area of the thermoplastic resin in the intermediate layer.Thereafter, based on the elution time of the thermoplastic resin in theintermediate layer and the calibration curve, an area corresponding tothe region of the polystyrene-equivalent molecular weight of 1000000 ormore of the thermoplastic resin in the intermediate layer is calculated.The value obtained by dividing the area corresponding to the region ofthe polystyrene-equivalent molecular weight of 1000000 or more of thethermoplastic resin in the intermediate layer by the peak area of thethermoplastic resin in the intermediate layer is expressed in percentage(%). Accordingly, the ratio (%) of the high molecular weight component Ywith the molecular weight y of 1000000 or more in the thermoplasticresin can be calculated. For example, the polystyrene-equivalentmolecular weight can be measured by using Gel Permeation Chromatography(GPC) device (produced by Hitachi High-technologies Corporation, “RI:L2490, autosampler: L-2200, pump: L-2130, column oven: L-2350, column:GL-A120-S and GL-A100MX-S in series”).

(Plasticizer)

The plasticizer in each of the interlayer films 2 to 4 and 21 is notparticularly limited. The plasticizer may be a publicly knownplasticizer. One plasticizer may be used alone or two or moreplasticizers may be used in combination as the above plasticizer.

Examples of the plasticizer include organic ester plasticizers such as amonobasic organic acid ester and a polybasic organic acid ester, andphosphoric acid plasticizers such as an organic phosphoric acidplasticizer and an organic phosphorous acid plasticizer. Among these, anorganic ester plasticizer is preferable. The plasticizer is preferably aliquid plasticizer.

Examples of the monobasic organic acid ester include, but notparticularly limited to, a glycol ester obtained through the reaction ofglycol and a monobasic organic acid, and an ester of a monobasic organicacid and triethylene glycol or tripropylene glycol. Examples of theglycol include triethylene glycol, tetraethylene glycol, andtripropylene glycol. Examples of the monobasic organic acid includebutanoic acid, isobutyric acid, caproic acid, 2-ethylbutanoic acid,heptylic acid, n-octyl acid, 2-ethylhexyl acid, n-nonylic acid, anddecylic acid.

Examples of the polybasic organic acid ester include, but notparticularly limited to, ester compounds such as one of a polybasicorganic acid and a C4 to C8 straight or branched chain alcohol. Examplesof the polybasic organic acid include adipic acid, sebacic acid, andazelaic acid.

Examples of the organic ester plasticizer include, but not particularlylimited to, triethylene glycol di-2-ethylbutyrate, triethylene glycoldi-2-ethylhexanoate, triethylene glycol dicaprylate, triethylene glycoldi-n-octanoate, triethylene glycol di-n-heptanoate, tetraethylene glycoldi-n-heptanoate, dibutyl sebacate, dioctylazelate, dibutylcarbitoladipate, ethylene glycol di-2-ethylbutyrate, 1,3-propylene glycoldi-2-ethylbutyrate, 1,4-butylene glycol di-2-ethylbutyrate, diethyleneglycol di-2-ethylbutyrate, diethylene glycol di-2-ethylhexanoate,dipropylene glycol di-2-ethylbutyrate, triethylene glycoldi-2-ethylpentanoate, tetraethylene glycol di-2-ethylbutyrate,diethylene glycol dicaprylate, dihexyl adipate, dioctyl adipate,hexylcyclohexyl adipate, a mixture of heptyl adipate and nonyl adipate,diisononyl adipate, diisodecyl adipate, heptyl nonyl adipate, dibutylsebacate, oil-modified alkyd sebacate, and a mixture of phosphate andadipate. An organic ester plasticizer other than these may be used.Adipates other than the above adipate may be used.

Examples of the organic phosphoric acid plasticizer include, but notparticularly limited to, tributoxyethyl phosphate, isodecyl phenylphosphate, and triisopropyl phosphate.

The plasticizer is preferably a diester plasticizer represented by thefollowing formula (I). The use of a diester plasticizer can furtherincrease the sound insulation of the laminated glass.

In formula (I), R1 and R2 each represent a C5 to C10 organic group, R3represents an ethylene group, an isopropylene group, or an n-propylenegroup, and p represents an integer of 3 to 10. R1 and R2 in formula (I)each preferably represent a C6 to C10 organic group.

The plasticizer preferably contains at least one kind among triethyleneglycol di-2-ethylhexanoate (3GO) and triethylene glycoldi-2-ethylbutyrate (3 GH).

The amount of the plasticizer in the interlayer film for a laminatedglass is not particularly limited.

In the case of the interlayer film 2 or 21 in which the thermoplasticresin contains the high molecular weight component X with an absolutemolecular weight of 1000000 or more at the specific ratio, the minimumamount of the plasticizer for each 100 parts by weight of thethermoplastic resin is preferably 40 parts by weight, more preferably 50parts by weight, still more preferably 55 parts by weight, andparticularly preferably 60 parts by weight. The maximum amount ispreferably 80 parts by weight, more preferably 78 parts by weight, stillmore preferably 75 parts by weight, and particularly preferably 72 partsby weight. Also, in the case of the interlayer film 2 or 21 in which thethermoplastic resin contains the high molecular weight component Y withthe molecular weight y of 1000000 or more at the specific ratio, theminimum amount of the plasticizer for each 100 parts by weight of thethermoplastic resin is preferably 40 parts by weight, more preferably 50parts by weight, still more preferably 55 parts by weight, andparticularly preferably 60 parts by weight. The maximum amount ispreferably 80 parts by weight, more preferably 78 parts by weight,further preferably 75 parts by weight, and particularly preferably 72parts by weight. If the amount of the plasticizer satisfies thepreferable minimum amount, the penetration resistance of the laminatedglass can be further increased. If the amount of the plasticizersatisfies the preferable maximum amount, the transparency of theinterlayer film or the multilayer interlayer film can be furtherincreased.

In the case of the interlayer films 3 and 4, the minimum amount of theplasticizer for each 100 parts by weight of the thermoplastic resin ispreferably 25 parts by weight, more preferably 30 parts by weight, andstill more preferably 35 parts by weight. The maximum amount ispreferably 50 parts by weight, more preferably 45 parts by weight, stillmore preferably 43 parts by weight, and particularly preferably 38 partsby weight. If the amount of the plasticizer satisfies the preferableminimum amount, the adhesion force of the interlayer film is increased,which leads to a further increase in the penetration resistance of thelaminated glass. If the amount of the plasticizer satisfies thepreferable maximum amount, the transparency of the interlayer film orthe multilayer interlayer film can be further increased.

In terms of further increasing the sound insulation of the laminatedglass, the amount of the plasticizer for each 100 parts by weight of thethermoplastic resin in the interlayer film 2 is preferably larger thanthe amount of the plasticizer for each 100 parts by weight of thethermoplastic resin in each of the interlayer films 3 and 4. In terms offurther increasing the sound insulation of the laminated glass, theamount of the plasticizer for each 100 parts by weight of thethermoplastic resin in the interlayer film 2 is larger than the amountof the plasticizer for each 100 parts by weight of the thermoplasticresin in each of the interlayer films 3 and 4 by preferably 5 parts byweight or more, more preferably 10 parts by weight or more, still morepreferably 15 parts by weight or more, and particularly preferably 20parts by weight or more.

(Other Components)

The interlayer films 2 to 4, and 21 each may contain, if desired,additives such as an ultraviolet ray absorbent, an antioxidant, a lightstabilizer, a flame retardant, an antistatic agent, a pigment, a dye, anadhesion regulator, a moisture resistant agent, a fluorescent bleach,and an infrared absorbent.

(Laminated Glass)

Each interlayer film for a laminated glass or multilayer interlayer filmfor a laminated glass according to the present invention is used toobtain a laminated glass.

FIG. 3 is a cross-sectional view schematically illustrating one exampleof a laminated glass using the multilayer interlayer film 1 in FIG. 1.

A laminated glass 11 in FIG. 3 is provided with a first laminated glasscomponent 12, a second laminated glass component 13, and the multilayerinterlayer film 1. The multilayer interlayer film 1 is sandwichedbetween the first laminated glass component 12 and the second laminatedglass component 13.

The first laminated glass component 12 is laminated on an outer surface3 a of the second interlayer film 3. The second laminated glasscomponent 13 is laminated on an outer surface 4 a of the thirdinterlayer film 4. Therefore, the laminated glass 11 has a structure inwhich the first laminated glass component 12, the second interlayer film3, the first interlayer film 2, the third interlayer film 4, and thesecond laminated glass component 13 are laminated in the stated order.

Examples of the first laminated glass component 12 and the secondlaminated glass component 13 include glass plates and PET (polyethyleneterephthalate) films. The laminated glass encompasses not only alaminated glass having an interlayer film or a multilayer interlayerfilm sandwiched between two glass plates but also a laminated glasshaving an interlayer film or a multilayer interlayer film sandwichedbetween a glass plate and a PET film. A laminated glass is a laminatedproduct provided with glass plate(s) preferably including at least oneglass plate.

Examples of the glass plate include inorganic glass and organic glass.Examples of the inorganic glass include float plate glass, heatabsorbing plate glass, heat reflecting glass, polished plate glass,molded plate glass, wire plate glass, and lined plate glass. The organicglass is a synthetic resin glass substituted for inorganic glass.Examples of the organic glass include polycarbonate plates andpoly(meth)acrylic resin plates. Examples of the poly(meth)acrylic resinplate include polymethyl (meth)acrylate plates.

The thickness of each of the first laminated glass component 12 and thesecond laminated glass component 13 is preferably 0.5 mm or larger, andmore preferably 1 mm or larger. The thickness is also preferably 5 mm orsmaller, and more preferably 3 mm or smaller. If the laminated glasscomponents 12 and 13 each are glass plates, the thickness of each glassplate is preferably within the range of 1 to 3 mm. If the laminatedglass components 12 and 13 each are PET films, the thickness of each PETfilm is preferably within the range of 0.03 to 0.5 mm.

The method of producing the laminated glass is not particularly limited.For example, sandwiching the interlayer film or the multilayerinterlayer film between the first laminated glass component and thesecond laminated glass component, and then removing the air remainingbetween the interlayer film or the multilayer interlayer film and thefirst laminated glass component and the second laminated glass componentby pressing the resulting product with pressure rollers, or by puttingthe product in a rubber bag for vacuum-sucking. Then, the product ispre-bonded at about 70° C. to 110° C. to obtain a laminate. Next, thelaminate is put into an autoclave or is pressed, so as to bepressure-bonded with a pressure of 1 to 1.5 MPa at about 120° C. to 150°C. Thus, the laminated glass can be obtained.

The laminated glass can be widely used for cars, rail cars, aircrafts,boats and ships, buildings, and the like. The laminated glass can beused in applications other than these uses. For example, the laminatedglass can be used for windshields, side glass, rear glass, and roofglass of cars.

Hereinafter, the present invention will be described in more detailbased on Examples. The present invention is not limited to theseExamples.

First, the following polyvinyl acetal resins A to Q, U to Z weresynthesized.

Synthesis Example 1 Synthesis of Polyvinyl Acetal Resin A

Ion-exchange water (2700 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2300 and a saponification degree of87.5 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 35% by weight of hydrochloric acid as a catalyst to adjust thehydrochloric acid concentration to 0.6% by weight. After the temperaturewas adjusted to 15° C., 14.2 g of n-butylaldehyde was added whilestirring to the solution. Upon further adding 170 g of n-butylaldehyde,a polyvinyl butyral resin in a white powder form was deposited. Fifteenminutes after the deposition, 35% by weight of hydrochloric acid wasadded to adjust the hydrochloric acid concentration to 3.9% by weight.The resulting mixture was heated to 45° C. and matured at 45° C. forthree hours. The solution was cooled and neutralized. Then, thepolyvinyl butyral resin was washed with water and dried to give apolyvinyl butyral resin A.

In the resulting polyvinyl butyral resin A, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 11.5%. In the resultingpolyvinyl butyral resin A, the ratio of the high molecular weightcomponent Y (polyvinyl butyral resin) with the molecular weight y of1000000 or more was 13.8%. The polyvinyl butyral resin A had a numberaverage molecular weight of 102000, a weight average molecular weight of750000, a hydroxyl content of 22.3 mol %, a degree of acetylation of12.5 mol %, and a degree of butyralization of 65.2 mol %.

Synthesis Example 2 Synthesis of Polyvinyl Acetal Resin B

Ion-exchange water (2700 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2300 and a saponification degree of87.5 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 35% by weight of hydrochloric acid as a catalyst to adjust thehydrochloric acid concentration to 0.6% by weight. After the temperaturewas adjusted to 15° C., 14.2 g of n-butylaldehyde was added whilestirring to the solution. Upon further adding 175 g of n-butylaldehyde,a polyvinyl butyral resin in a white powder form was deposited. Fifteenminutes after the deposition, 35% by weight of hydrochloric acid wasadded to adjust the hydrochloric acid concentration to 3.9% by weight.The resulting mixture was heated to 45° C. and matured at 45° C. forthree hours. The solution was cooled and neutralized. Then, thepolyvinyl butyral resin was washed with water and dried to give apolyvinyl butyral resin B.

In the resulting polyvinyl butyral resin B, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 15.4%. In the resultingpolyvinyl butyral resin B, the ratio of the high molecular weightcomponent Y (polyvinyl butyral resin) with the molecular weight y of1000000 or more was 17.3%. The polyvinyl butyral resin B had a numberaverage molecular weight of 105000, a weight average molecular weight of1175000, a hydroxyl content of 22.0 mol %, a degree of acetylation of12.5 mol %, and a degree of butyralization of 65.5 mol %.

Synthesis Example 3 Synthesis of Polyvinyl Acetal Resin C

Ion-exchange water (2700 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2300 and a saponification degree of87.5 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 35% by weight of hydrochloric acid as a catalyst to adjust thehydrochloric acid concentration to 0.6% by weight. After the temperaturewas adjusted to 15° C., 14.2 g of n-butylaldehyde was added whilestirring to the solution. Upon further adding 186 g of n-butylaldehyde,a polyvinyl butyral resin in a white powder form was deposited. Fifteenminutes after the deposition, 35% by weight of hydrochloric acid wasadded to adjust the hydrochloric acid concentration to 3.9% by weight.The resulting mixture was heated to 45° C. and matured at 45° C. forthree hours. The solution was cooled and neutralized. Then, thepolyvinyl butyral resin was washed with water and dried to give apolyvinyl butyral resin C.

In the resulting polyvinyl butyral resin C, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 20.9%. In the resultingpolyvinyl butyral resin C, the ratio of the high molecular weightcomponent Y (polyvinyl butyral resin) with the molecular weight y of1000000 or more was 24.5%. The polyvinyl butyral resin C had a numberaverage molecular weight of 120000, a weight average molecular weight of2565000, a hydroxyl content of 23.0 mol %, a degree of acetylation of12.5 mol %, and a degree of butyralization of 64.5 mol %.

Synthesis Example 4 Synthesis of Polyvinyl Acetal Resin D

Ion-exchange water (2400 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 1700 and a saponification degree of99.2 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.45% by weight. After the temperature wasadjusted to 15° C., 27 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 181 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 2.1% by weight. The resulting mixturewas heated to 48° C. and matured at 48° C. for two hours. The solutionwas cooled and neutralized. Then, the polyvinyl butyral resin was washedwith water and dried to give a polyvinyl butyral resin D.

In the resulting polyvinyl butyral resin D, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 8%. In the resulting polyvinylbutyral resin D, the ratio of the high molecular weight component Y(polyvinyl butyral resin) with the molecular weight y of 1000000 or morewas 9.1%. The polyvinyl butyral resin D had a number average molecularweight of 100000, a weight average molecular weight of 520000, ahydroxyl content of 21.7 mol %, a degree of acetylation of 0.8 mol %,and a degree of butyralization of 77.5 mol %.

Synthesis Example 5 Synthesis of Polyvinyl Acetal Resin E

Ion-exchange water (3000 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2300 and a saponification degree of87.5 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.6% by weight. After the temperature wasadjusted to 15° C., 14 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 165 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 1.3% by weight. The resulting mixturewas heated to 42° C. and matured at 42° C. for three hours. The solutionwas cooled and neutralized. Then, the polyvinyl butyral resin was washedwith water and dried to give a polyvinyl butyral resin E.

In the resulting polyvinyl butyral resin E, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 16.4%. In the resultingpolyvinyl butyral resin E, the ratio of the high molecular weightcomponent Y (polyvinyl butyral resin) with the molecular weight y of1000000 or more was 18.7%. The polyvinyl butyral resin E had a numberaverage molecular weight of 125000, a weight average molecular weight of1062000, a hydroxyl content of 27.0 mol %, a degree of acetylation of12.5 mol %, and a degree of butyralization of 60.5 mol %.

Synthesis Example 6 Synthesis of Polyvinyl Acetal Resin F

Ion-exchange water (2700 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 1700 and a saponification degree of99.2 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 35% by weight of hydrochloric acid as a catalyst to adjust thehydrochloric acid concentration to 0.2% by weight. After the temperaturewas adjusted to 15° C., 23 g of n-butylaldehyde was added while stirringto the solution. Upon further adding 143 g of n-butylaldehyde, apolyvinyl butyral resin in a white powder form was deposited. Fifteenminutes after the deposition, 35% by weight of hydrochloric acid wasadded to adjust the hydrochloric acid concentration to 1.8% by weight.The resulting mixture was heated to 60° C. and matured at 60° C. for twohours. The solution was cooled and neutralized. Then, the polyvinylbutyral resin was washed with water and dried to give a polyvinylbutyral resin F.

The polyvinyl butyral resin F had a number average molecular weight of125000, a weight average molecular weight of 1062000, a hydroxyl contentof 30.4 mol %, a degree of acetylation of 0.8 mol %, and a degree ofbutyralization of 68.8 mol %.

Synthesis Example 7 Synthesis of Polyvinyl Acetal Resin G

Ion-exchange water (3000 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2300 and a saponification degree of87.5 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.6% by weight. After the temperature wasadjusted to 15° C., 14.2 g of n-butylaldehyde was added while stirringto the solution. Upon further adding 165 g of n-butylaldehyde, apolyvinyl butyral resin in a white powder form was deposited. Fifteenminutes after the deposition, 60% by weight of nitric acid was added toadjust the nitric acid concentration to 1.3% by weight. The resultingmixture was heated to 55° C. and matured at 55° C. for three hours. Thesolution was cooled and neutralized. Then, the polyvinyl butyral resinwas washed with water and dried to give a polyvinyl butyral resin G.

In the resulting polyvinyl butyral resin G, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 7.3%. In the resulting polyvinylbutyral resin G, the ratio of the high molecular weight component Y(polyvinyl butyral resin) with the molecular weight y of 1000000 or morewas 8.8%. The polyvinyl butyral resin G had a number average molecularweight of 85000, a weight average molecular weight of 509000, a hydroxylcontent of 23.0 mol %, a degree of acetylation of 12.5 mol %, and adegree of butyralization of 64.5 mol %.

Synthesis Example 8 Synthesis of Polyvinyl Acetal Resin H

Ion-exchange water (2400 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 1700 and a saponification degree of99.2 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.45% by weight. After the temperature wasadjusted to 15° C., 27 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 181 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 2.1% by weight. The resulting mixturewas heated to 55° C. and matured at 55° C. for two hours. The solutionwas cooled and neutralized. Then, the polyvinyl butyral resin was washedwith water and dried to give a polyvinyl butyral resin H.

In the resulting polyvinyl butyral resin H, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 6.5%. In the resulting polyvinylbutyral resin H, the ratio of the high molecular weight component Y(polyvinyl butyral resin) with the molecular weight y of 1000000 or morewas 7.6%. The polyvinyl butyral resin H had a number average molecularweight of 112000, a weight average molecular weight of 500000, ahydroxyl content of 21.2 mol %, a degree of acetylation of 0.8 mol %,and a degree of butyralization of 78.0 mol %.

Synthesis Example 9 Synthesis of Polyvinyl Acetal Resin I

Ion-exchange water (3000 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2300 and a saponification degree of86.9 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.6% by weight. After the temperature wasadjusted to 15° C., 13 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 180 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 1.7% by weight. The resulting mixturewas heated to 52° C. and matured at 52° C. for two hours. The solutionwas cooled and neutralized. Then, the polyvinyl butyral resin was washedwith water and dried to give a polyvinyl butyral resin I.

In the resulting polyvinyl butyral resin I, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 9%. In the resulting polyvinylbutyral resin I, the ratio of the high molecular weight component Y(polyvinyl butyral resin) with the molecular weight y of 1000000 or morewas 11.6%. The polyvinyl butyral resin I had a number average molecularweight of 165000, a weight average molecular weight of 550000, ahydroxyl content of 22.9 mol %, a degree of acetylation of 13.1 mol %,and a degree of butyralization of 64.0 mol %.

Synthesis Example 10 Synthesis of Polyvinyl Acetal Resin J

Ion-exchange water (2700 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2500 and a saponification degree of99.2 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.6% by weight. After the temperature wasadjusted to 15° C., 13 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 200 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 2.0% by weight. The resulting mixturewas heated to 52° C. and matured at 52° C. for two hours. The solutionwas cooled and neutralized. Then, the polyvinyl butyral resin was washedwith water and dried to give a polyvinyl butyral resin J.

In the resulting polyvinyl butyral resin J, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 9.5%. In the resulting polyvinylbutyral resin J, the ratio of the high molecular weight component Y(polyvinyl butyral resin) with the molecular weight y of 1000000 or morewas 11.8%. The polyvinyl butyral resin J had a number average molecularweight of 167000, a weight average molecular weight of 448000, ahydroxyl content of 21.2 mol %, a degree of acetylation of 0.8 mol %,and a degree of butyralization of 78.0 mol %.

Synthesis Example 11 Synthesis of Polyvinyl Acetal Resin K

Ion-exchange water (3000 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2320 and a saponification degree of94.4 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.6% by weight. After the temperature wasadjusted to 15° C., 13 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 205 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 2.3% by weight. The resulting mixturewas heated to 51° C. and matured at 51° C. for two hours. The solutionwas cooled and neutralized. Then, the polyvinyl butyral resin was washedwith water and dried to give a polyvinyl butyral resin K.

In the resulting polyvinyl butyral resin K, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 9.8%. In the resulting polyvinylbutyral resin K, the ratio of the high molecular weight component Y(polyvinyl butyral resin) with the molecular weight y of 1000000 or morewas 12.0%. The polyvinyl butyral resin K had a number average molecularweight of 155000, a weight average molecular weight of 530000, ahydroxyl content of 21.9 mol %, a degree of acetylation of 5.6 mol %,and a degree of butyralization of 72.5 mol %.

Synthesis Example 12 Synthesis of Polyvinyl Acetal Resin L

Ion-exchange water (2700 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 1700 and a saponification degree of87.5 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.6% by weight. After the temperature wasadjusted to 15° C., 13 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 175 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 1.9% by weight. The resulting mixturewas heated to 53° C. and matured at 53° C. for two hours. The solutionwas cooled and neutralized. Then, the polyvinyl butyral resin was washedwith water and dried to give a polyvinyl butyral resin L.

In the resulting polyvinyl butyral resin L, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 7.5%. In the resulting polyvinylbutyral resin L, the ratio of the high molecular weight component Y(polyvinyl butyral resin) with the molecular weight y of 1000000 or morewas 9.0%. The polyvinyl butyral resin L had a number average molecularweight of 158000, a weight average molecular weight of 546000, ahydroxyl content of 23.5 mol %, a degree of acetylation of 12.5 mol %,and a degree of butyralization of 64.0 mol %.

Synthesis Example 13 Synthesis of Polyvinyl Acetal Resin M

Ion-exchange water (3200 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2300 and a saponification degree of99.2 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.4% by weight. After the temperature wasadjusted to 15° C., 17 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 170 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 2.1% by weight. The resulting mixturewas heated to 55° C. and matured at 55° C. for two and a half hours. Thesolution was cooled and neutralized. Then, the polyvinyl butyral resinwas washed with water and dried to give a polyvinyl butyral resin M.

In the resulting polyvinyl butyral resin M, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 6.9%. In the resulting polyvinylbutyral resin M, the ratio of the high molecular weight component Y(polyvinyl butyral resin) with the molecular weight y of 1000000 or morewas 8.4%. The polyvinyl butyral resin M had a number average molecularweight of 148000, a weight average molecular weight of 410000, ahydroxyl content of 20.4 mol %, a degree of acetylation of 0.8 mol %,and a degree of butyralization of 78.8 mol %.

Synthesis Example 14 Synthesis of Polyvinyl Acetal Resin N

Ion-exchange water (3200 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2300 and a saponification degree of87.8 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.5% by weight. After the temperature wasadjusted to 15° C., 11 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 160 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 1.7% by weight. The resulting mixturewas heated to 57° C. and matured at 57° C. for three hours. The solutionwas cooled and neutralized. Then, the polyvinyl butyral resin was washedwith water and dried to give a polyvinyl butyral resin N.

In the resulting polyvinyl butyral resin N, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 7.2%. In the resulting polyvinylbutyral resin N, the ratio of the high molecular weight component Y(polyvinyl butyral resin) with the molecular weight y of 1000000 or morewas 8.9%. The polyvinyl butyral resin N had a number average molecularweight of 152000, a weight average molecular weight of 430000, ahydroxyl content of 23.4 mol %, a degree of acetylation of 12.2 mol %,and a degree of butyralization of 64.4 mol %.

Synthesis Example 15 Synthesis of Polyvinyl Acetal Resin O

Ion-exchange water (3000 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2000 and a saponification degree of93.5 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.6% by weight. After the temperature wasadjusted to 15° C., 11 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 170 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 1.8% by weight. The resulting mixturewas heated to 58° C. and matured at 58° C. for two hours. The solutionwas cooled and neutralized. Then, the polyvinyl butyral resin was washedwith water and dried to give a polyvinyl butyral resin O.

In the resulting polyvinyl butyral resin O, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 6.6%. In the resulting polyvinylbutyral resin O, the ratio of the high molecular weight component Y(polyvinyl butyral resin) with the molecular weight y of 1000000 or morewas 7.6%. The polyvinyl butyral resin O had a number average molecularweight of 138000, a weight average molecular weight of 402000, ahydroxyl content of 20.4 mol %, a degree of acetylation of 6.5 mol %,and a degree of butyralization of 73.1 mol %.

Synthesis Example 16 Synthesis of Polyvinyl Acetal Resin P

Ion-exchange water (2700 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 1700 and a saponification degree of98.9 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.7% by weight. After the temperature wasadjusted to 15° C., 15 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 175 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 1.6% by weight. The resulting mixturewas heated to 52° C. and matured at 52° C. for two hours. The solutionwas cooled and neutralized. Then, the polyvinyl butyral resin was washedwith water and dried to give a polyvinyl butyral resin P.

In the resulting polyvinyl butyral resin P, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 5.3%. In the resulting polyvinylbutyral resin P, the ratio of the high molecular weight component Y(polyvinyl butyral resin) with the molecular weight y of 1000000 or morewas 6.8%. The polyvinyl butyral resin P had a number average molecularweight of 140000, a weight average molecular weight of 390000, ahydroxyl content of 21.0 mol %, a degree of acetylation of 1.1 mol %,and a degree of butyralization of 77.9 mol %.

Synthesis Example 17 Synthesis of Polyvinyl Acetal Resin Q

Ion-exchange water (3350 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 1700 and a saponification degree of87.8 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.5% by weight. After the temperature wasadjusted to 15° C., 15 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 150 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 1.7% by weight. The resulting mixturewas heated to 57° C. and matured at 57° C. for two and a half hours. Thesolution was cooled and neutralized. Then, the polyvinyl butyral resinwas washed with water and dried to give a polyvinyl butyral resin Q.

In the resulting polyvinyl butyral resin Q, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 5.1%. In the resulting polyvinylbutyral resin Q, the ratio of the high molecular weight component Y(polyvinyl butyral resin) with the molecular weight y of 1000000 or morewas 6.4%. The polyvinyl butyral resin Q had a number average molecularweight of 143000, a weight average molecular weight of 395000, ahydroxyl content of 22.8 mol %, a degree of acetylation of 12.2 mol %,and a degree of butyralization of 65.0 mol %.

Synthesis Example 18 Synthesis of Polyvinyl Acetal Resin U

Ion-exchange water (3200 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2380 and a saponification degree of90.5 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.55% by weight. After the temperature wasadjusted to 15° C., 13 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 180 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 1.8% by weight. The resulting mixturewas heated to 55° C. and matured at 55° C. for three hours. The solutionwas cooled and neutralized. Then, the polyvinyl butyral resin was washedwith water and dried to give a polyvinyl butyral resin U.

In the resulting polyvinyl butyral resin U, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 9.4%. In the resulting polyvinylbutyral resin U, the ratio of the high molecular weight component Y(polyvinyl butyral resin) with the molecular weight y of 1000000 or morewas 11.5%. The polyvinyl butyral resin U had a number average molecularweight of 170000, a weight average molecular weight of 530000, ahydroxyl content of 23 mol %, a degree of acetylation of 9.5 mol %, anda degree of butyralization of 67.5 mol %.

Synthesis Example 19 Synthesis of Polyvinyl Acetal Resin V

Ion-exchange water (3400 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2450 and a saponification degree of82.5 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.65% by weight. After the temperature wasadjusted to 15° C., 13 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 175 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 1.9% by weight. The resulting mixturewas heated to 55° C. and matured at 55° C. for two and a half hours. Thesolution was cooled and neutralized. Then, the polyvinyl butyral resinwas washed with water and dried to give a polyvinyl butyral resin V.

In the resulting polyvinyl butyral resin V, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 8.5%. In the resulting polyvinylbutyral resin V, the ratio of the high molecular weight component Y(polyvinyl butyral resin) with the molecular weight y of 1000000 or morewas 10.9%. The polyvinyl butyral resin V had a number average molecularweight of 150000, a weight average molecular weight of 500000, ahydroxyl content of 23.2 mol %, a degree of acetylation of 17.5 mol %,and a degree of butyralization of 59.3 mol %.

Synthesis Example 20 Synthesis of Polyvinyl Acetal Resin W

Ion-exchange water (3500 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2500 and a saponification degree of77.7 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.5% by weight. After the temperature wasadjusted to 15° C., 15 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 185 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 2.0% by weight. The resulting mixturewas heated to 51° C. and matured at 51° C. for two hours. The solutionwas cooled and neutralized. Then, the polyvinyl butyral resin was washedwith water and dried to give a polyvinyl butyral resin W.

In the resulting polyvinyl butyral resin W, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 12.5%. In the resultingpolyvinyl butyral resin W, the ratio of the high molecular weightcomponent Y (polyvinyl butyral resin) with the molecular weight y of1000000 or more was 15%. The polyvinyl butyral resin W had a numberaverage molecular weight of 170000, a weight average molecular weight of650000, a hydroxyl content of 24 mol %, a degree of acetylation of 22.3mol %, and a degree of butyralization of 53.7 mol %.

Synthesis Example 21 Synthesis of Polyvinyl Acetal Resin X

Ion-exchange water (2900 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 1700 and a saponification degree of92.6 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.5% by weight. After the temperature wasadjusted to 15° C., 14 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 200 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 2.1% by weight. The resulting mixturewas heated to 50° C. and matured at 50° C. for three hours. The solutionwas cooled and neutralized. Then, the polyvinyl butyral resin was washedwith water and dried to give a polyvinyl butyral resin X.

In the resulting polyvinyl butyral resin X, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 17.3%. In the resultingpolyvinyl butyral resin X, the ratio of the high molecular weightcomponent Y (polyvinyl butyral resin) with the molecular weight y of1000000 or more was 19.8%. The polyvinyl butyral resin X had a numberaverage molecular weight of 160000, a weight average molecular weight of670000, a hydroxyl content of 22 mol %, a degree of acetylation of 7.4mol %, and a degree of butyralization of 70.6 mol %.

Synthesis Example 22 Synthesis of Polyvinyl Acetal Resin Y

Ion-exchange water (3300 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2350 and a saponification degree of95.8 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.6% by weight. After the temperature wasadjusted to 15° C., 14 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 200 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 2.3% by weight. The resulting mixturewas heated to 52° C. and matured at 52° C. for two and a half hours. Thesolution was cooled and neutralized. Then, the polyvinyl butyral resinwas washed with water and dried to give a polyvinyl butyral resin Y.

In the resulting polyvinyl butyral resin Y, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 14.2%. In the resultingpolyvinyl butyral resin Y, the ratio of the high molecular weightcomponent Y (polyvinyl butyral resin) with the molecular weight y of1000000 or more was 17.6%. The polyvinyl butyral resin Y had a numberaverage molecular weight of 160000, a weight average molecular weight of620000, a hydroxyl content of 21.9 mol %, a degree of acetylation of 4.2mol %, and a degree of butyralization of 73.9 mol %.

Synthesis Example 23 Synthesis of Polyvinyl Acetal Resin Z

Ion-exchange water (3700 ml) and a polyvinyl alcohol (300 g) having anaverage polymerization degree of 2400 and a saponification degree of98.7 mol % were placed in a reactor vessel equipped with a stirrer, anddissolved by heating while stirring to give a solution. To the solutionwas added 60% by weight of nitric acid as a catalyst to adjust thenitric acid concentration to 0.6% by weight. After the temperature wasadjusted to 15° C., 17 g of n-butylaldehyde was added while stirring tothe solution. Upon further adding 205 g of n-butylaldehyde, a polyvinylbutyral resin in a white powder form was deposited. Fifteen minutesafter the deposition, 60% by weight of nitric acid was added to adjustthe nitric acid concentration to 2.3% by weight. The resulting mixturewas heated to 53° C. and matured at 53° C. for three hours. The solutionwas cooled and neutralized. Then, the polyvinyl butyral resin was washedwith water and dried to give a polyvinyl butyral resin Z.

In the resulting polyvinyl butyral resin Z, the ratio of the highmolecular weight component X (polyvinyl butyral resin) with an absolutemolecular weight of 1000000 or more was 11.3%. In the resultingpolyvinyl butyral resin Z, the ratio of the high molecular weightcomponent Y (polyvinyl butyral resin) with the molecular weight y of1000000 or more was 15.3%. The polyvinyl butyral resin Z had a numberaverage molecular weight of 165000, a weight average molecular weight of600000, a hydroxyl content of 20.5 mol %, a degree of acetylation of 1.3mol %, and a degree of butyralization of 78.2 mol %.

Moreover, polyvinyl butyral resins R to T described below were prepared.

Polyvinyl butyral resin R: hydroxyl content: 30.4 mol %, degree ofacetylation: 0.8 mol %, degree of butyralization: 68.8 mol %

Polyvinyl butyral resin S: hydroxyl content: 30.5 mol %, degree ofacetylation: 0.8 mol %, degree of butyralization: 68.7 mol %

Polyvinyl butyral resin T: hydroxyl content: 30.7 mol %, degree ofacetylation: 0.8 mol %, degree of butyralization: 68.5 mol %

Using each of the thus obtained polyvinyl acetal resins A to Z, amultilayer interlayer film for a laminated glass and a laminated glasswere produced.

Example 1 (1) Production of Multilayer Interlayer Film

To 100 parts by weight of the obtained polyvinyl butyral resin A wasadded 60 parts by weight of a plasticizer of triethylene glycoldi-2-ethylhexanoate (3GO). The mixture was sufficiently kneaded by amixing roll, so that a resin composition for an intermediate layer wasobtained. Next, to 100 parts by weight of the obtained polyvinyl butyralresin F was added 37.5 parts by weight of a plasticizer of triethyleneglycol di-2-ethylhexanoate (3GO). The mixture was sufficiently kneadedby a mixing roll, so that a resin composition for a surface layer wasobtained.

The resin composition for an intermediate layer and the resincompositions for a surface layer were co-extruded, whereby a multilayerinterlayer film in which a surface layer (thickness: 350 μm), anintermediate layer (thickness: 100 μm), and a surface layer (thickness:350 μm) were laminated in the stated order was produced.

(2) Production of Laminated Glass for Penetration Resistance Test

The obtained multilayer interlayer film was cut into a size of 30 cm(length)×30 cm (width). Next, the multilayer interlayer film wassandwiched between two sheets of transparent float glass (30 cm(length)×30 cm (width)×2.5 mm (thickness)), and thereby a laminate wasobtained. The laminate was put into a rubber bag and deaerated for 20minutes at the degree of vacuum of 2.6 kPa. The deaerated product wasput into an oven to further stand at 90° C. for 30 minutes forvacuum-pressing, so that the laminate was pressure-bonded in advance.The preliminary pressure-bonded laminate was pressure-bonded in anautoclave at 135° C. and a pressure of 1.2 MPa for 20 minutes. Thereby,a laminated glass to be used for a penetration resistance test wasprepared.

(3) Production of Laminated Glass for Sound Insulation Measurement

A laminated glass to be used for sound insulation measurement wasproduced by the same procedure as that for preparing the laminated glassfor a penetration resistance test, except that the multilayer interlayerfilm was cut into a size of 30 cm (length)×2.5 cm (width) and each sheetof the transparent float glass used had a size of 30 cm (length)×2.5 cm(width)×2.5 mm (thickness).

(4) Production of Laminated Glass for Bubble Formation Tests A and B

The obtained multilayer interlayer film was cut into a size of 30 cm(length)×15 cm (width), and the cut-out film was left to stand at 23° C.for 10 hours. Here, both faces of the obtained multilayer interlayerfilm were embossed with the ten-point average roughness of 30 μm. In thecut-out multilayer interlayer film, four 6 mm-diameter through holeswere formed on respective four intersection points each located at adistance of 8 cm inward in the lengthwise direction from an end of themultilayer interlayer film and also at a distance of 5 cm inward in thetransverse direction from an end of the multilayer interlayer film.

The multilayer interlayer film having the through holes was sandwichedbetween two sheets of the transparent float glass (30 cm (length)×15 cm(width)×2.5 mm (thickness)), so that a laminate was obtained. Theperiphery of the laminate was sealed 2 cm from the end with a sealingagent by thermal fusion bonding to encapsulate the air remaining in theembossed parts and in the through holes. The laminate waspressure-bonded at 135° C. and a pressure of 1.2 MPa for 20 minutes, sothat the remaining air was dissolved into the multilayer interlayerfilm. Thereby, sheets of laminated glass to be used for bubble formationtests were obtained.

Examples 2 to 21 and Comparative Examples 1 to 9

A multilayer interlayer film and a laminated glass were produced by thesame procedure as that for Example 1, except that the formulations forthe first interlayer film, the second interlayer film and the thirdinterlayer film were changed to the values shown in the following Tables1 to 3.

(Evaluation)

(1) Sound Insulation

The laminated glass was vibrated with a vibration generator for adumping test (“Vibration generator G21-005D” produced by Shinken Co.,Ltd.). The vibration characteristics obtained thereby were amplifiedwith a mechanical impedance measuring device (“XG-81” produced by Rion),and the vibration spectrum was analyzed with an FET spectrum analyzer(“FFT analyzer HP3582A” produced by YOKOGAWA Hewlett-Packard, Ltd.).

From the ratio of the loss factor determined thereby and the resonancefrequency with the laminated glass, a graph showing the relation betweensound frequency (Hz) and sound transmission loss (dB) at 20° C. wasgenerated, and the minimum sound transmission loss (TL value) around thesound frequency of 2,000 Hz was determined. A higher TL value indicateshigher sound insulation. A TL value of 35 dB or higher was evaluated as“◯”, and a TL value of lower than 35 dB was evaluated as “x”. Tables 1to 3 below show the results.

(2) Bubble Formation Test A (Bubble Formation State)

Five sheets of the laminated glass for bubble formation test A wereproduced for each multilayer interlayer film, and were left to stand ina 50° C. oven for 100 hours. After the standing, the sheets of thelaminated glass were observed by eye in a plan view for the presence orabsence of bubbles and the sizes of the bubbles. The bubble formationwas determined based on the following criteria.

[Criteria of Bubble Formation State in Forming Test A]

The bubbles in each of the five sheets of the laminated glass wereapproximated with an ellipse, and the ellipse area was set as a bubbleformation area. The average value of the ellipse areas observed in therespective five sheets of the laminated glass was determined, and theratio (percentage) of the average value of the ellipse areas (bubbleformation areas) to the area of the sheet of the laminated glass (30cm×15 cm) was determined.

◯◯: No bubble was observed in all the five sheets of the laminated glass

◯: Ratio of average value of ellipse area (bubble formation area) waslower than 5%

Δ: Ratio of average value of ellipse area (bubble formation area) was 5%or higher and lower than 10%

x: Ratio of average value of ellipse area (bubble formation area) was10% or higher.

(3) Bubble Formation Test B (Bubble Formation State)

Thirty sheets of the laminated glass for bubble formation test B wereproduced for each multilayer interlayer film, and were left to stand inan oven at 50° C. for 24 hours. After the standing, the sheets of thelaminated glass were observed by eye to confirm the number of sheets ofthe laminated glass in which forms were observed, and evaluated based onthe following evaluation criteria.

[Criteria of Bubble Formation State in Forming Test B]

◯◯: Forms were observed by eye in at most five sheets of the laminatedglass.

◯: Forms were observed by eye in at least 6 sheets and at most 10 sheetsof the laminated glass.

Δ: Forms were observed by eye in at least 11 sheets and at most 15sheets of the laminated glass.

x: Forms were observed by eye in at least 16 sheets of the laminatedglass.

(4) Penetration Resistance

The surface temperature of sheets of the laminated glass (30 cm(length)×30 cm (width)) used for the penetration resistance test wasadjusted to 23° C. Subsequently, according to JIS R 3212, a rigid spherehaving a mass of 2260 g and a diameter of 82 mm was dropped from aheight of 4 m on the center of each of six sheets of the laminatedglass. The laminated glass was considered to have passed the test if allthe six sheets of the laminated glass prevented the rigid sphere frompenetrating therethrough within five seconds after the rigid sphere hitthe sheets. The laminated glass was considered to have failed the testif three or less sheets of the laminated glass prevented the rigidsphere from penetrating therethrough within five seconds after the rigidsphere hit the sheets. In the case of four sheets, another six sheets ofthe laminated glass were tested again on the penetration resistance. Inthe case of five sheets, another sheet of the laminated glass wastested. The glass was considered to have passed the test if the othersheet prevented the rigid sphere from penetrating therethrough withinfive seconds after the rigid sphere hit the sheet. In the same way, arigid sphere having a mass of 2260 g and a diameter of 82 mm was droppedfrom heights of 5 m and 6 m on the center of each of six sheets of thelaminated glass to evaluate the penetration resistance of the laminatedglass.

(Measurement of Absolute Molecular Weight)

The absolute molecular weight and the polystyrene-equivalent molecularweight for giving the ratios of the high molecular weight components Xand Y in the synthesis examples 1 to 5, and 7 to 23 were obtained in abelow-mentioned manner, using the surface layers and the intermediatelayer separated from the obtained multilayer interlayer film.

For measuring the absolute molecular weight, first, the multilayerinterlayer film was left to stand in a constant temperature and humidityroom (humidity: 30% (±3%), temperature: 23° C.) for one month. After theone-month standing, the surface layers and the intermediate layer wereseparated from the multilayer interlayer film. The separatedintermediated layer was dissolved in tetrahydrofuran (THF) to prepare a0.1% by weight solution. The resulting solution was analyzed with a GelPermeation Chromatography (GPC) device (produced by HitachiHigh-technologies Corporation, “RI: L2490, autosampler: L-2200, pump:L-2130, column oven: L-2350, column: GL-A120-S and GL-A100MX-S inseries”). Meanwhile, the GPC device was connected to a light scatteringdetector for GPC (produced by Viscotek, “Model 270 (RALS+VISCO”), andthereby chromatography can be performed in each of the detectors. Thepeaks of the polyvinyl butyral resin components in the chromatograms bythe RI detector and the RALS detector were analyzed using an analysissoftware (Omni SEC), so that an absolute molecular weight of thepolyvinyl butyral resin at each elution time was obtained. The ratio ofthe area of the region corresponding to the molecular weight of thepolyvinyral resin of 1000000 or more in the peak area of the polyvinylbutyral resin detected by the RI detector was expressed in a percentage(%).

The following equations are satisfied for the peaks of the respectivecomponents in the chromatograms.A _(RI) =c×(dn/dc)×K _(RI)  Equation (1)A _(RALS) =c×M×(dn/dc)² ×K _(RALS)  Equation (2)

In the equations, c represents the polymer concentration; (dn/dc)represents the increment of the refractive index; M represents theabsolute molecular weight; and K represents the system's coefficient.

A specific measurement procedure is as follows. First, using apolystyrene standard sample (produced by Viscotek, PolyCAL (registeredtrademark) TDS-PS-NB Mw=98390, dn/dc=0.185) with known c, M and (dn/dc),a 0.1% by weight THF solution thereof is prepared. Then, the system'scoefficient K of each of the detectors is obtained using the equations(1) and (2) from the results of the GPC measurement of the resultingpolystyrene solution.

Next, the separated intermediate layer was dissolved in THF to prepare aTHF solution thereof. An absolute molecular weight M of the polyvinylbutyral resin was obtained from the results of the GPC measurement ofthe polyvinyl butyral resin solution using the equations (1) and (2).

Meanwhile, for analysis of the intermediate layer (containing apolyvinyl butyral resin and a plasticizer), it is necessary to obtainthe concentration of the polyvinyl butyral resin in the polyvinylbutyral resin solution. The concentration of the polyvinyl butyral resinwas calculated according to the results of (measurement of amount ofplasticizer) below.

(Measurement of Molecular Weight y)

In the same manner as the measuring method of an absolute molecularweight, a polystyrene-equivalent molecular weight was determined by gelpermeation chromatography (GPC), and the ratio (%) of the high molecularweight component Y with the molecular weight y of 1000000 or more in thepolyvinyl butyral resin was calculated based on the ratio of the area ofthe region corresponding to the molecular weight of 1000000 or more inthe peak area (GPC measurement result) detected by the RI detector.

In order to determine the polystyrene-equivalent molecular weight, GPCmeasurement was performed on polystyrene standard samples with knownmolecular weight. The polystyrene standard samples used (“ShodexStandard SM-105” and “Shodex Standard SH-75” produced by Showa DenkoK.K.) were 14 samples having weight-average molecular weights of 580,1260, 2960, 5000, 10100, 21000, 28500, 76600, 196000, 630000, 1130000,2190000, 3150000, and 3900000. An approximation straight line, obtainedby plotting the weight-average molecular weight against the elution timeat the peak top of the respective standard sample peaks, was used as acalibration curve. The surface layers and the intermediate layer wereseparated from the multilayer interlayer film that has been left tostand in a constant temperature and humidity room (humidity: 30% (±3%),temperature: 23° C.) for one month. The separated intermediate layer wasdissolved in tetrahydrofuran (THF) so that a 0.1% by weight solutionthereof was prepared. The solution was analyzed with a GPC device todetermine the peak area of the thermoplastic resin in the intermediatelayer. Thereafter, based on the elution time of the thermoplastic resinin the intermediate layer and the calibration curve, an areacorresponding to the region of the polystyrene-equivalent molecularweight of 1000000 or more of the thermoplastic resin in the intermediatelayer was calculated. The value obtained by dividing the areacorresponding to the region of the polystyrene-equivalent molecularweight of 1000000 or more of the thermoplastic resin in the intermediatelayer by the peak area of the thermoplastic resin in the intermediatelayer was expressed by percentage (%). Accordingly, the ratio (%) of thehigh molecular weight component Y with the molecular weight y of 1000000or more in the thermoplastic resin was calculated.

(Measurement of Amount of Plasticizer)

Plasticizer-THF solutions were prepared by dissolving the plasticizer inTHF in a manner that the amounts of the plasticizer were set to 10% byweight, 15% by weight, 20% by weight, 25% by weight, 30% by weight, 35%by weight, 40% by weight, 45% by weight, and 50% by weight. Theplasticizer-THF solutions obtained were measured by GPC so that a peakarea of the plasticizer was obtained. An approximation straight line wasobtained by plotting the peak area of the plasticizer against theconcentration of the plasticizer. Next, a solution of the intermediatelayer dissolved in THF was measured by GPC. The amount of theplasticizer was obtained from the peak area of the plasticizer using theapproximation straight line.

Tables 1 to 3 show the results. In the tables 1 to 3 below, “PVB” refersto polyvinyl butyral, “PVA” refers to polyvinyl alcohol, “3GO” refers totriethylene glycol di-2-ethylhexanoate, and “3 GH” refers to triethyleneglycol di-2-ethylbutylate.

TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Formulation of PVB resinKind A A B B C C first interlayer Ratio of high molecular % 11.5 11.515.4 15.4 20.9 20.9 film weight component X Ratio of high molecular %13.8 13.8 17.3 17.3 24.5 24.5 weight component Y Average degree of 23002300 2300 2300 2300 2300 polymerization of PVA Hydroxyl content mol %22.3 22.3 22.0 22.0 23.0 23.0 Degree of acetylation mol % 12.5 12.5 12.512.5 12.5 12.5 Degree of butyralization mol % 65.2 65.2 65.5 65.5 64.564.5 Amount of PVB resin Parts by 100 100 100 100 100 100 weightPlasticizer Kind 3GO 3GO 3GO 3GO 3GO 3GO Amount Parts by 60 60 60 60 6060 weight Formulation of PVB resin Kind F F F F F F second and Hydroxylcontent mol % 30.4 30.4 30.4 30.4 30.4 30.4 third interlayer Degree ofacetylation mol % 0.8 0.8 0.8 0.8 0.8 0.8 films Degree of butyralizationmol % 68.8 68.8 68.8 68.8 68.8 68.8 Amount of PVB resin Parts by 100 100100 100 100 100 weight Plasticizer Kind 3GO 3GO 3GO 3GO 3GO 3GO AmountParts by 37.5 38.5 37.5 38.5 37.5 38.5 weight Evaluation Soundinsulation: TL value ∘ ∘ ∘ ∘ ∘ ∘ Bubble formation test A ∘ Δ ∘ ∘ ∘∘ ∘Bubble formation test B ∘ ∘ ∘ ∘ ∘∘ ∘∘ Penetration resistance 4 m passedpassed passed passed passed passed 5 m passed passed passed passedpassed passed 6 m passed passed passed passed passed passed Ex. 7 Ex. 8Ex. 9 Ex. 10 Ex. 11 Formulation of PVB resin Kind D D E E A firstinterlayer Ratio of high molecular % 8.0 8.0 16.4 16.4 11.5 film weightcomponent X Ratio of high molecular % 9.1 9.1 18.7 18.7 13.8 weightcomponent Y Average degree of 1700 1700 2300 2300 2300 polymerization ofPVA Hydroxyl content mol % 21.7 21.7 27.0 27.0 22.3 Degree ofacetylation mol % 0.8 0.8 12.5 12.5 12.5 Degree of butyralization mol %77.5 77.5 60.5 60.5 65.2 Amount of PVB resin Parts by 100 100 100 100100 weight Plasticizer Kind 3GO 3GO 3GO 3GO 3GH Amount Parts by 60 60 6060 60 weight Formulation of PVB resin Kind F F F F F second and Hydroxylcontent mol % 30.4 30.4 30.4 30.4 30.4 third interlayer Degree ofacetylation mol % 0.8 0.8 0.8 0.8 0.8 films Degree of butyralization mol% 68.8 68.8 68.8 68.8 68.8 Amount of PVB resin Parts by 100 100 100 100100 weight Plasticizer Kind 3GO 3GO 3GO 3GO 3GH Amount Parts by 37.538.5 37.5 38.5 37.5 weight Evaluation Sound insulation: TL value ∘ ∘ ∘ ∘∘ Bubble formation test A ∘ Δ ∘∘ ∘∘ ∘ Bubble formation test B Δ Δ ∘∘ ∘∘Δ Penetration resistance 4 m passed passed passed passed passed 5 mpassed passed passed passed passed 6 m passed passed passed passedpassed

TABLE 2 Comp. Comp. Comp. Comp. Ex 1 Ex. 2 Ex. 3 Ex. 4 Ex. 12 Ex. 13 Ex.14 Formulation of PVB resin Kind G G H H I J K first interlayer Ratio ofhigh molecular % 7.3 7.3 6.5 6.5 9.0 9.5 9.8 film weight component XRatio of high molecular % 8.8 8.8 7.6 7.6 11.6 11.8 12.0 weightcomponent Y Average degree of 2300 2300 1700 1700 2300 2500 2320polymerization of PVA Hydroxyl content mol % 23.0 23.0 21.2 21.2 22.921.2 21.9 Degree of acetylation mol % 12.5 12.5 0.8 0.8 13.1 0.8 5.6Degree of butyralization mol % 64.5 64.5 78.0 78.0 64.0 78.0 72.5 Amountof PVB resin Parts by 100 100 100 100 100 100 100 weight PlasticizerKind 3GO 3GO 3GO 3GO 3GO 3GO 3GO Amount Parts by 70 75 70 75 60 60 60weight Formulation of PVB resin Kind F F F F R S R second and Hydroxylcontent mol % 30.4 30.4 30.4 30.4 30.4 30.5 30.4 third interlayer Degreeof acetylation mol % 0.8 0.8 08 0.8 0.8 0.8 0.8 films Degree ofbutyralization mol % 68.8 68.8 68.8 68.8 68.8 68.7 68.8 Amount of PVBresin Parts by 100 100 100 100 100 100 100 weight Plasticizer Kind 3GO3GO 3GO 3GO 3GO 3GO 3GO Amount Parts by 37.5 38.5 37.5 38.5 37.5 39.537.5 weight Evaluation Sound insulation: TL value ∘ ∘ ∘ ∘ ∘ ∘ ∘ Bubbleformation test A x x x x Δ Δ Δ Bubble formation test B x x x x ∘ ∘ ∘Penetration resistance 4 m passed passed passed passed passed passedpassed 5 m passed passed passed passed passed passed passed 6 m passedpassed passed passed passed passed passed Comp. Comp. Comp. Comp. Comp.Ex. 15 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Formulation of PVB resin Kind L M NO P Q first interlayer Ratio of high molecular % 7.5 6.9 7.2 6.6 5.3 5.1film weight component X Ratio of high molecular % 9.0 8.4 8.9 7.6 6.86.4 weight component Y Average degree of 1700 2300 2300 2000 1700 1700polymerization of PVA Hydroxyl content mol % 23.5 20.4 23.4 20.4 21.022.8 Degree of acetylation mol % 12.5 0.8 12.2 6.5 1.1 12.2 Degree ofbutyralization mol % 64.0 78.8 64.4 73.1 77.9 65.0 Amount of PVB resinParts by 100 100 100 100 100 100 weight Plasticizer Kind 3GO 3GO 3GO 3GO3GO 3GO Amount Parts by 60 60 60 60 60 60 weight Formulation of PVBresin Kind T F F F F F second and Hydroxyl content mol % 30.7 30.4 30.430.4 30.4 30.4 third interlayer Degree of acetylation mol % 0.8 0.8 0.80.8 0.8 0.8 films Degree of butyralization mol % 68.5 68.8 68.8 68.868.8 68.8 Amount of PVB resin Parts by 100 100 100 100 100 100 weightPlasticizer Kind 3GO 3GO 3GO 3GO 3GO 3GO Amount Parts by 37.5 37.5 37.537.5 37.5 37.5 weight Evaluation Sound insulation: TL value ∘ ∘ ∘ ∘ ∘ ∘Bubble formation test A Δ x x x x x Bubble formation test B Δ x x x x xPenetration resistance 4 m passed passed passed passed passed passed 5 mpassed passed passed passed passed passed 6 m passed passed passedpassed passed passed

TABLE 3 Ex. 16 Ex.17 Ex. 18 Ex. 19 Ex. 20 Ex. 21 Formulation of PVBresin Kind U V W X Y Z first interlayer Ratio of high molecular % 9.48.5 12.5 17.3 14.2 11.3 film weight component X Ratio of high molecular% 11.5 10.9 15 19.8 17.6 15.3 weight component Y Average degree of 23802450 2500 1700 2350 2400 polymerization of PVA Hydroxyl content mol % 2323.2 24 22 21.9 20.5 Degree of acetylation mol % 9.5 17.5 22.3 7.4 4.21.3 Degree of butyralization mol % 67.5 59.3 53.7 70.5 73.9 78.2 Amountof PVB resin Parts by 100 100 100 100 100 100 weight Plasticizer Kind3GO 3GO 3GO 3GO 3GO 3GO Amount Parts by 60 60 60 60 60 60 weightFormulation of PVB resin Kind F F F F F F second and Hydroxyl contentmol % 30.4 30.4 30.4 30.4 30.4 30.4 third interlayer Degree ofacetylation mol % 0.8 0.8 0.8 0.8 0.8 0.8 films Degree of butyralizationmol % 68.8 68.8 68.8 68.8 68.8 68.8 Amount of PVB resin Parts by 100 100100 100 100 100 weight Plasticizer Kind 3GO 3GO 3GO 3GO 3GO 3GO AmountParts by 37.5 37.5 37.5 37.5 37.5 37.5 weight Evaluation Soundinsulation: TL value ∘ ∘ ∘ ∘ ∘ ∘ Bubble formation test A ∘ ∘ ∘ ∘∘ ∘∘ ∘Bubble formation test B Δ Δ ∘ ∘∘ ∘ Δ Penetration resistance 4 m passedpassed passed passed passed passed 5 m passed passed passed passedpassed passed 6 m passed passed passed passed passed passed

EXPLANATION OF SYMBOLS

-   1 Multilayer interlayer film-   2 First interlayer film-   2 a One face-   2 b The other face-   3 Second interlayer film-   3 a Outer surface-   4 Third interlayer film-   4 a Outer surface-   11 Laminated glass-   12 First laminated glass component-   13 Second laminated glass component-   21 Interlayer film

The invention claimed is:
 1. A multilayer interlayer film for alaminated glass, comprising: a first interlayer film for a laminatedglass that contains a polyvinyl acetal resin as a thermoplastic resinand a plasticizer, a second interlayer film for a laminated glass thatcontains a polyvinyl acetal resin as a thermoplastic resin and aplasticizer, and the second interlayer film is laminated on one face ofthe first interlayer film for a laminated glass, and a third interlayerfilm for a laminated glass that contains a polyvinyl acetal resin as athermoplastic resin and a plasticizer, and the third interlayer film islaminated on the other face of the first interlayer film for a laminatedglass, the polyvinyl acetal resin in the first interlayer film having ahydroxyl content of 21.5 mol % or higher and at most 28 mol %, whereinthe polyvinyl acetal resin in the first interlayer film contains a highmolecular weight component with an absolute molecular weight of 1000000or more, and the ratio of the high molecular weight component in thepolyvinyl acetal resin of the first interlayer film is 7.4% or higher,or the polyvinyl acetal resin in the first interlayer film for alaminated glass contains a high molecular weight component with apolystyrene-equivalent molecular weight of 1000000 or more, and theratio of the high molecular weight component in the polyvinyl acetalresin of the first interlayer film is 9% or higher.
 2. The multilayerinterlayer film for a laminated glass according to claim 1, wherein thepolyvinyl acetal resin in the first interlayer film for a laminatedglass contains a high molecular weight component with an absolutemolecular weight of 1000000 or more, and the ratio of the high molecularweight component in the polyvinyl acetal resin of the first interlayerfilm is 7.4% or higher.
 3. A laminated glass comprising: a firstlaminated, glass component, a second laminated glass component, and amultilayer interlayer film sandwiched between the first laminated glasscomponent and the second laminated glass component, wherein themultilayer interlayer film is the multilayer interlayer film for alaminated glass according to claim
 2. 4. The multilayer interlayer filmfor a laminated glass according to claim 1 or 2, wherein an amount ofthe plasticizer for each 100 parts by weight of the polyvinyl acetalresin in the first interlayer film for a laminated glass is within arange of 40 to 80 parts by weight.
 5. The multilayer interlayer film fora laminated glass according to claim 1, wherein the polyvinyl acetalresin in the first interlayer film for a laminated glass contains a highmolecular weight component with a polystyrene-equivalent molecularweight of 1000000 or more, and the ratio of the high molecular weightcomponent in the polyvinyl acetal resin of the first interlayer film is9% or higher.
 6. The multilayer interlayer film for a laminated glassaccording to claim 1, wherein an amount of the plasticizer for each 100parts by weight of the polyvinyl acetal resin in the first interlayerfilm for a laminated glass is larger than an amount of the plasticizerfor each 100 parts by weight of the polyvinyl acetal resin in the secondinterlayer film for a laminated glass.
 7. The multilayer interlayer filmfor a laminated glass according to claim 1, wherein an amount of theplasticizer for each 100 parts by weight of the polyvinyl acetal resinin the first interlayer film for a laminated glass is larger than anamount of the plasticizer for each 100 parts by weight of the polyvinylacetal resin in the third interlayer film for a laminated glass.
 8. Themultilayer interlayer film for a laminated glass according to claim 1,wherein the polyvinyl acetal resin in the first interlayer film for alaminated glass has a degree of acetylation of at most 8 mol % and adegree of acetalization of 70 mol % or higher.
 9. The multilayerinterlayer film for a laminated glass according to claim 1, wherein thepolyvinyl acetal resin in the first interlayer film for a laminatedglass has a degree of acetylation of higher than 8 mol %.
 10. Alaminated glass comprising: a first laminated glass component, a secondlaminated glass component, and a multilayer interlayer film sandwichedbetween the first laminated glass component and the second laminatedglass component, wherein the multilayer interlayer film is themultilayer interlayer film for a laminated glass according to claim 1.